Passive Optical Network (PON) is an optical access network, which may not have any active devices such as electronic equipment and an electronic power supply and so on. The PON system may mainly comprise an Optical Line Terminal (OLT), an Optical Distribution Network (ODN) and an Optical Network Unit (ONU). Where, the OLT may provide the access network with an interface between the network side and the core network, and may be connect to each ONU via an ODN. An ONU may provide an interface to the user side for the access network, which may provide multi-service flows such as voice, data, video etc. in accessing ODN.